Multi-purpose alloys of controlled homogeneity



Uni S ate Pa MULTI-PURPOSE ALLOYS 0F CONTROLLED HOMOGENEITY 1 SamuelFreedman, La Mesa, Califi, assignor to' Chemal- Icy-Electronics Corp, anDiego fiounty, Calif., a corpora'tion of .California No Drawing.original application March 31, 1952, Se-

rial No. muses, now Patent No. 2,796,345, dated June a 18, 1957. Dividedand this application April30, 1957, Serial No. 670,623 v v I 5 claim;or. 75-178) This invention relates to'welding or soldering alloys and toprocesses of making such alloys.

This application is a divisional application of application Ser. No.279,696, now Patent No. 2,796,345, issued June 18, v1957.

vOne object of this invention is to provide a welding or soldering alloywhich can be used to unite metal parts including aluminum parts, Withoutthe necessity of em! ploying careful cleaning procedure or fluxes,andwithouttthe necessity of employing the drastic cleaning meaS-J uresorzusing the corrosive fluxes or specialized equipment previouslyrequired with. aluminum welding or soldering processes in order toremove the tenacious'oxide film from the surface of the aluminum.

Another object is to provide a welding or soldering A whereupon thewelding rod melts and flows by capillary attraction into and along thejunction without previously applying. a fiuX, uniting'the partstenaciously in a firm and permanent joint, f A

Another object isr to provide a welding or soldering alloy for. unitingmetal parts, including aluminum or aluminum'alloyparts, wherein thewelded area, after. welding or soldering, has a strength at the junctionwhich is greater than the strength of the adjacent metal, so that it theparts are subjected to excessive force, they will break adjacent thejunction, but not at the junction itself,

evenv if the welding alloy has approximately the samethickness at thejunction as the thickness ofthe adjoining aluminum or aluminum alloyparts which have been welded.

Another object is to aluminumalloy parts,- which alloy has a silveryappearance at the welded junction and" which will not rust or provide awelding or soldering. alloy 'for uniting metal parts, includingaluminumor;

2,927,856 I Patented Mar. 8, 1960 'ice alloyfor uniting metal parts,including aluminum or aluininum alloy parts, wherein special grooving orother special-preparation' of' the edges of the aluminum partstrating-through oxide layers or'coatings of impurities and t to beunited is not necessary; because the welding alloy of the presentinvention penetrates through theoxide film to the interior of the metaltomake a strong fusion, and flows readily without sp-atteriug orcreating lumps, and without the production of the fumes or odorsproduced when-fluxes are used as in prior processes of uniting aluminurn or aluminum alloy. parts.

Another object is to provide a process of making a welding or solderingalloy having the characteristics-set forth in the preceding objects,wherein the process enables the introduction of chemicals into the alloywhile it is in a molten state, without the production of dangerousexplosions which have hitherto characterized the attempted mixing ofsuch chemicals with molten metal, these chemicals giving the alloy itsproperties of peneof' flowing easily 'andnaturally by capillaryattraction into the junction between the parts to be united. Anotherobject is to provide a process of making a Welding or soldering" alloyof the foregoing character wherein the chemicals are introduced into themolten alloy by being minutely-subdivided into particles which areseparated from one another by inert material, such "as by 'mixing thechemicals into porous slag or other.

porous material which will act similarly, thereby producing a myriad"oi'separated minute explosions instead of f a single large one. 1 1

Another object' is to provide a process of making a welding or solderingalloy, aslsett forth in the object. immediately above, wherein thedanger of explosion in introducingthe chemicals into the molten alloy isfurther reduced by theuse of a layer of carbon, such as fine. grain'charcoal -forming an insulating blanket, over the top of themolten-alloy, the porous material containing the chemicals beingplacedupon thiscarbon layer and pushed through it into the molten alloybeneath it,' ,;thfe

slag, after'being freed from its chemicals, floating to: the

surface where it is skimmed off.

. Another object is to reduce the melting temperature of; solderingalloys by the homogenization of normally' incompatible, metals such aszinc and lead.

, molten alloy by'being' minutely subdivided into particles corrode, andwhichcan be readily'fmachined, polished,

plated or. painted.

' Another object is. to provide a welding or soldering alloy, foruniting metal parts, including aluminum or. aluminum:alloy'p arts,which. alloy can bev employed by inexperienced persons withoutspecialtraining and without the need for any of the special preparatorymeasures previously required in uniting aluminum parts, and notrequiring Welding hoods, coloredglasses or special eye protection. 7

Another object is to provide a aluminum alloy parts, wherein the weldedarea has a veryfine grain structure without'porosity, and, whereinwelding or solderingalloy for uniting metal parts, including aluminum orsoft'solder will adhereso'as to enable the'at tachment separatedfrom'one another by inert material.

Another object'is to cleanse molten metals. of super- 7 fluousimpuritieswhile in a molten state. I I Another object is to createmetals having reducedcorrosive and galvanic actions.

Another objec't is to create metals which are moreheatless and lubelessbecause of their inherent electricali properties andtheir improvedhomogeneityin alloy formi Another object is to provide metal alloyswhich in the presence of'moisturecause the conversion of the latter intoescapablehydrogen gas;

alloy that requires no coolant.

Another object. is to provide a metal alloy' which elec Another objectis to provide a free machining-metal? trifies and decomposes moisture'incontact or during im mersion.

Anothertob'ject is to provide a. metal alloy which can penetratealuminum {surface oxides and travel in the! direction of most m e'tal'by capillary'action instead at burning through the thin thickness oflight gauge metal.

Hitherto, the welding or soldering of aluminum has been a difficultprocedure requiring specialized knowledge, skilled workmanship, andcareful preparation of the aluminum or aluminum alloy parts to bewelded. The tenacious film of oxide which adheres to the surface ofaluminum or aluminum alloys, unless removed by careful preparation or bythe use of corrosive fluxes, effectively prevented the obtaining of astrong welded junction between the partsbeing united. Furthermore, thefact that aluminum melts suddenly at 1217 F. without any advanceindication, such as discoloration, of nearing the melting point, hasmade high temperature welding procedures dangerous, due to thepossibility of destroying the parts themselves by their suddendisintegration. The corrosive fluxes hitherto used have also caused thecreation of annoying fumes and odors, and protective goggles, hoods orthe like have been required because of the danger to the eyes of thewelding material spattering or sputtering. Nevertheless, without firstapplying a flux to create a flow path, the welding or soldering alloywould not flow along or into the junction of the parts to be united. Thewelding alloy of the present invention, as made by the process ofthe-present invention, eliminates these defects and accomplishes the newresults and advantages set forth in the above-stated objects.

In preparing the alloy of the present invention, the following metalsand metal alloys are melted together in a crucible in the followingproportions to provide the metallic ingredients:

Example I V Pounds Yellow brass (30% zinc and 70% copper) 8 Aluminum 840-60 solder (40% tin and 60% lead) 1.5

Silver (.l%) .1

Nickel-(1%) .1

Zinc, to make up a 100 pound batch or 82.

The chemical ingredients are next prepared in approximately thefollowing proportions, for a 100 pound batch of the above metalingredients:

Commercial muriatic acid (hydrochloric acid), up to 0.50 gallon.

The chemical ingredients are mixed together thoroughly and the acidadded and stirred into the dry ingredients until a thin or waterypaste-like mass is produced.

Meanwhile, the metal ingredients in the crucible have been heated untilthey reach the temperature of approximately 1450 F. and a layer of finegrain powdered charcoal of approximately a half-inch thickness isdeposited on top of the molten metal to form an insulating blanket. Whenthis charcoal layer has become red in color, the wet mass of chemicalingredients is deposited entirely over the top of the charcoal blanketin a thick layer. Using a suitable pushing device, such as a metal rod,the chemical mass is forced down through the charcoal blanket into themolten metal mixture, at small area at a time. The charcoal blanketshields the remainder of the mass from explosion or excessive reaction.As the chemical mass is pushed into the molten metal mixture in thecrucible, a multitude of tiny reactions occurs throughout it, instead ofa single large explosion, due to the fact that the chemical particlesare separated from one another by the porous inert slag and by the.Particles of charcoal... As each portion which has beenfpushed down intothe molten metal mixture is absorbed into the latter, another portion ispushed down and so on, until each portion of the chemical mass or layerhas been pushed through the insulating charcoal blanket, a small area ata time.

After all of the wet chemical mass has been pushed downward into themolten metal mixture in the crucible, the entire mixture is stirredthoroughly to release all of the chemicals from the pores of the copperslag and to cause the tiny reactions and explosions to be completed.When this has been done, and the slag has lost its chemicalimpregnations by these reactions and minute explosions, the slag floatsto the surface of the molten metal mixture, along with other impuritiesor superfluous materials, these being skimmed from the surface of themolten metal mixture, leaving the latter in its finished state. Thechemically-impregnated alloy thus formed is then poured out and formedinto suitable shapes such as rods, bars or ingots.

During the period in which the chemical ingredients are being pusheddownward through the charcoal blanket into the molten metal mixture,corrosive fumes are emitted which must be carefully disposed of or theywill discolor paint, corrode ferrous metals, and cause annoyance topersons in the vicinity. After the alloy has been made in the abovemanner, however, it' may be subsequently remelted without the formationof such fumes. The chemically-impregnated metal alloy remaining afterthe process has been completed is a finely homogenized, high qualityalloy which is easily machined, plated or V mally incompatible.

- is the Waste slag produced in copper smelting plants, and

isuseful because of its porosity and inert characteristics. it will'beobvious that other porous materials which are similarly inert may alsobe employed to subdivide the chemical ingredients in the above mannerand therebyconvert an otherwise dangerous single explosion into amultitude of tiny harmless explosions and reactions.

The effect of the chemical ingredients thus incorporated into the metalalloy impart to the alloy thecapability of flowing naturally and easilyby capillary attraction when the alloy is applied to the junction ofmetal parts, such as aluminum, to be united, without the previous use ofa flux. Hitherto, it has been necessary to apply a flux in order to forma flux path at the junction of the metal parts to be united, orotherwise the I welding metal does not flow well, and does not easilyvery thin gauge aluminum, this resulting from the chemienter thejunction between the metal parts to be united.

Thus, the soldering alloy undergoes capillary action in callyhomogenized metal ingredients such as zinc, lead,

incompatible.

The proportions and, indeed, the components, of the metallic mixture arenot critical and many variations may be used. In place of the brass,pure copper or even bronze can be employed, more copper giving greaterstrength. The nickel and silver components are mere traces which producebetter uniting of the metal components with one another. The chemicalcomponents of the alloy enable the alloy to penetrate the oxide film onaluminum without wire brushing or other previous preparation and topenetrate the crack or other junction between the parts to be united andto emerge on the opposite side thereof.

Proof that the efiect of the chemical ingredients remain in the alloy isfound in the fact that shavings of by, a voltmeter, milliammeter or.cathode. ray oscilloscope when leads or electrodes connected thereto areinserted in the water. Moreover, when the alloy particles or shavlngshave been permitted to remain in the water,

the surface. Each of these bubbles explodes upon the application of amatch,,showing that chemicals in the alloy. shavings produce hydrogenand other gases when placed in water. Thus, the powderized solderingalloy, inherently has soil conditioning properties when planted inthesoilfor the reason that the evolution of gases therefrom in the presenceof moisture tends to aerate the soil and the electrical actionaccompanying the gas evolution elevates the soil temperature. -Aerationof the soil promotes an increased rate of growth and germination, theintensity of which depends on how 'finely the alloy is powderized. Astill. more powerful effect is obtained when salt water is used.Moreover, if the alloy is prepared in the form of a powder, this powertendsgasbubbles will emerge from the water and form on i to come tothesurface of the water and float thereon even though it Specific gravityor weight is nearly seven times that of water.

In the use of the alloy of the invention in soldering or welding metalparts, such as aluminum, the extreme and exacting cleaning measurespreviously employed are unnecessary. The parts to be united, if notalready sat- 1 that the alloy of thepresent invention may be used to.

parts, namely use of sufficient-heat to cause surface fusion of themetal parts to be united; and (3) welding with fusion of the parts to beunited, accompanied by capil-' lary action, namely .welding wherein thealloy flows along the parts and through the junction thereof withoutthe.

previous use of a flux. a

The alloy of the present invention may be used with soft-solderablemetals such as copper by blending together standard lead-tin softsolders with an. alloy combination of zinc, lead and tin.

The use of the alloy of the present invention for soldering, brazing orwelding metals other than aluminum alloys, such as'the zinc base metalmentioned above,

is carried out in a similar manner except that the working margin of:temperature between the zinc in the parts to be united and the presentalloy is much smaller since aluminum melts at the'relatively hightemperature of 1217 F., whereas zinc melts at the relatively lowtemperature of 713 F. To lower the melting temperature of the alloy ofthe present invention, therefore, the silver and nickel should beomitted and the proportionate amount of brass reduced, as these metalscontribute to raising the melting point. Experiments have also shownsolder, braze or weld magnesium, but considerably more care andvigilance is necessary because magnesium, al-

or'by the application of a flame, such. as from) a. gas.

torch, Bunsen burner, spirit lamp or the like.

When the parts have been so heated, apiece, such asarod, of the alloy ofthe present invention is rubbed against the parts and passed to and froalong their proposed junction. Since the mclting point of the weldingalloy of the present invention is below 825 F., it melts and flowsfreely at that temperature, forming a silvery liquid resembling mercury.No flux is necessary to cause the alloy to flow, penetrate or adhere. Asthe rod is rubbed back and forth along the junction, the alloy melts andflows easily and naturally by capillary attraction into the junction,where it quickly solidifies. At the same time, it attacks the oxide filmon the aluminum or aluminum alloy, and penetrates below that film intothe metal itself, so that a strong-weld is obtained. The

either;

such higher temperatures where the parent metal itself has beendisturbed and fusion has taken place.

The metal parts when united by the alloy. of the presentinvention, maybe machined by the usual techniques and equipment, as the alloy machineseasily and is also easily painted or plated. V The use of the alloy ofthe present invention may be summarized by stating that, it may beemployed for (1 welding of the metal parts without fusion, namelysoldering or brazing; 2) weldingwith fusion' of the metal though meltingat about 1200 F., occasionally catches fire'at about l0 00 F. Here also,the working margin of temperature is rather small and consequentlyoperations must be conducted with caution.

In the process of preparing the alloy of the present invention, ifthefurnace heat is inadvertently raised to too:high a temperatureso'that some of the metal ingredientsstart to volatilize, particularlythe zinc, the operator immediately covers the top of the molten metal.in the crucible with a layer of willow charcoal, which stops thevola'tilization. Normally, however, the operator does not use morecharcoal after the layer which he initially applies, and waits untilthis charcoal powder has become completely red beforehe attempts to pushthechemical found best to permit the charcoal to ignite and burn at theouter periphery of the crucible and gradually consume itself/toward thecenter of the blanket, whereupon the flame disappears and the'top of themolten metal in" the crucible becomes tightly sealed with a red charcoalcoating, i n

To improve the free machining characteristics of the alloy, theproportion of solder may be increased, the machinability increasing asthe proportion of solder is increased, Thus, in the formula given'above, instead of 1.5 pounds of solder for a hundred pound batch, .asmuch as 3 to 5'pou'nds of solder may be beneficially employed.

"Additional sulphur is employed occasionally, if for example, it isfound that high melting components of the alloy are not properlymelting, even though the temperature has been raised to the point whereother ingredients, suchas zinc, are ready to volatilize. In thatinstance, the operator throws yellow sulphur into the portion of thecrucible where the unmel-ted brass is located, whereupon a blue flamearises and increases the temperature in the immediate vicinity of thesulphur,

causing the brass to melt readily. Thus, the addition-of sulphur has theopposite effect from the additionofcharwhere to produce salts such aschlorides which increase the tenacity of adhesion of the alloy inwelding or soldering, and thus render the use of a separate fluxunneces-i sary. The charcoal blanket, however, reduces the tendency ofthe muriatic acid to volatilize, especially if only small portions ofthe chemical ingredients are pushed through the charcoal layer into themolten metals at a given time. The copper slag of the formula, beinginert and heat-resistant, apparently takes no part in the chemicalreaction but merely serves as a vehicle or carrier or modulator in amanner analogous to the phenomenon of modulation in radio wavetransmission. alloy of the present invention is characterized by thepresence of chemicals in solution with the metals, the effects of thesechemicals remaining in the alloy upon solidification and enhancing theflow of the alloy by capillary action during welding without the use ofa separate flux.

The use of the alloy of the present invention enables aluminum to besubstituted for critically scarce copper in many installations orapplications where aluminum was previously considered unsatisfactorybecause of the diificulty of Welding or soldering it. The present alloymay also be used to coat aluminum wire by a procedure analogous totinning copper Wire so that the thus coated aluminum may besoft-soldered to other metals. The present alloy may also be used in theform of a molten bath for tinning aluminum articles for soldering themor for hermetically sealing them.

What I claim is:

1. A fluxless soldering or Welding alloy comprising per 100 pounds ofmetal by weight about 8% aluminum, up to 8% yellow brass (30% zinc, 70%copper), about 1 /2% 40-60 solder (40% tin, 60% lead) and the remainderzinc, and the non-volatized and non-removed residues of copper slag upto 3 pounds, sulphur up to 1.25 pounds, willow charcoal up to .75 poundand muriatic acid up to .5 gallon, allhomogenized together.

2. An alloy suitable for fluxless soldering or welding which comprisesper hundred pounds of metal by weight yellow brass (30% zinc, 70%copper) about 8%, aluminum about 8%, 40-60 solder (40% tin, and 60%lead) Thus, the

about 1 /2%, silver about .1%, nickel about .1% and zinc about 82.3%,and the non-volati zed and non-removable residues of copper slag up to 3pounds, sulphur up to 1.25 pounds, willow charcoal up to .75 pound andmuriatic acid'upto .5 gallon; all homogenized together.

3. An alloy suitable for fluxless soldering or welding which per hundredpounds of metal by weight yellow brass (30% zinc, 70% copper) about 8%,alumi-- num about 8%, 40-60 solder (40% tin, lead) about 1 /2% and zincabout 82.5%, and the non-volatized and non-removable residues of copperslag up to 3 pounds, sulphur up to 1.25 pounds, willow charcoal up to.75 pound and muriatic acid up to .5 gallon; all homogenized together. 7

4. An alloy suitable for fluxless soldering or welding which per hundred.pounds of metal by weight copper about 5.6%, aluminum about 8%, 40-60solder (40% tin, 60% lead) about 1 /z% and zinc about 84.9%, and thenon-volatized and non-removable residues of copper slag up to 3 pounds,sulphur up to 1.25 pounds, willow charcoal up to .75 pound and muriaticacid up to .5

gallon; all homogenized together. 1

5. An alloy suitable for fiuxless soldering or welding which per hundredpounds of metal by weight copper about 8% (aluminum about 8%, 40-60solder (40% tin, 60% lead) about 1 /2% and zinc about 82.5%, and thenon-volatized and non-removable residues of copper slag up to 3 pounds,sulphur up to 1.25 pounds, willow charcoal up to .75 pound and muriaticacid up to .5

gallon; all homogenized together.

References Cited in the file of this patent UNITED STATES PATENTS

1. A FLUXLESS SOLDERING OR WELDING ALLOY COMPRISING PER 100 POUNDS OFMETAL BY WEIGHT ABOUT 8% ALUMINUM, UP TO 8% YELLOW BRASS (30% ZINC 70%COPPER), ABOUT 11/2% 40-60 SOLDER (40% TIN, 60% LEAD) AND THE REMAINDERZINC, AND THE NON-VOLATIZED AND NON-REMOVED RESIDUES OF COPPER SLAG UPTO 3 POUNDS, SULPHUR UP TO 1.25 POUNDS, WILLOW CHARCOAL UP TO .75 POUNDAND MURIATIC ACID UP TO .5 GALLON, ALL HOMOGENIZED TOGETHER.